Impact of Basic Fibroblast Growth Factor Treatment on Left Ventricular Ejection Fraction, Remodeling and Collagen Content After Acute Anterior Myocardial Infarction: Basic fibroblast growth factor (bFGF), an angiogenic growth factor, has been reported to reduce infarct size (IS) and to improve ejection fraction (EF) in a canine model of acute myocardial infarction (AMI); however, the impact of bFGF treatment on left ventricular remodeling (LVR) and collagen content (CC) after AMI is unknown. We examined the effects of bFGF on EF, LVR and CC in a canine AMI model. Permanent LAD occlusion was induced in 29 dogs by inflating a previously implanted hydraulic balloon occluder. bFGF (100 ?g/kg) or saline were injected via a LA catheter systemically 10 min (T1), 6 hours (T2) and daily, 2-7 days after AMI (T3-T8). Dogs were randomized to 3 cohorts: early bFGF (T1,T2) then saline T3-T8; delayed bFGF (T3-T8) with early saline T1,T2; or saline T1-T8. Tissue CC was assessed after staining the slides with picrosirius red. EF measured 1 day after AMI was comparable in all groups; however, end-diastolic volume (EDV) was significantly reduced in early bFGF cohort (48+/-4 mL) vs. controls (58+/-3 mL, p=0.04). At 1 week, EDV was significantly reduced in both early and delayed bFGF cohorts relative to controls: EDV=41+/-2, 41+/-3 and 54+/-4 mL, respectively (early vs. control p=0.01; delayed vs. control p=0.02), with no difference in EF. Collagen % within the RR was 0.48+/-0.08 in early bFGF, 0.62+/-0.13 in delayed bFGF, and 0.87+/-0.14 in controls respectively (early vs. controls p<0.02; delayed vs. controls p=n.s.). Thus, although bFGF did not improve EF in this model, reductions in EDV and in collagen content suggest a salutary effect on remodeling.